(1) Field of the Invention
The present invention relates to the field of means for assembling two bodies together by causing a nut and a bolt to co-operate. The present invention relates more particularly to devices for fastening a nut to the surface of a body by means of an assembly plate interposed between them.
The present invention provides such a fastening device comprising a plate having a nut and fitted with means for fastening to the surface of a body.
(2) Description of Related Art
It is common practice to assemble two bodies together by means of two assembly members that co-operate with each other. In a common method of assembly, the assembly members are respectively of the bolt type and of the nut type. It is known to bond a nut on a body by means of a fastener device making use of an assembly plate that is provided with the nut and that is fitted with means for fastening to the surface of the body. The plate may incorporate the nut, but in order to reduce the cost of obtaining the fastener device, it is preferable for the plate and the nut to be separate items made of respective materials having different mechanical properties. The body on which the plate is applied is in particular in the form of a slab or an analogous structural element that is generally plane and of small thickness. Such a slab makes it easy for an attachment member to be pressed axially against the plate and the body. By way of example, such an attachment member may be a rivet or a screw, or indeed any other analogous attachment member suitable for applying opposing axial thrusts between two generally plane elements for assembling together. Since the plate and the body are both generally plane in shape and are placed superposed one on the other, the attachment member bears axially simultaneously against opposite large faces respectively of the plate and of the body.
The plate is of a generally plane shape having a large face constituting a seat pressed against the body that receives it, and opposite another large face forming an access face that is oriented outwards relative to the plate installed on the body. The plate commonly includes a housing for holding the nut captive, which housing opens out to the access face of the plate. The nut is held captive inside the housing by means for preventing it from turning and by means for retaining it axially. The turning prevention means may for example be arranged as a blocking polygon, providing co-operation between an outside shape of the nut, which is polygonal, and lateral abutments included in the housing. At least two sides of the polygon bear respectively against the side abutments so as to oppose any turning of the nut by the bolt with which it is to co-operate. By way of example, the axial retention means are arranged as an axial abutment included in the plate. The axial abutment, e.g. as formed by a shoulder forming part of the housing or at least a claw, is arranged in register with the housing and applies axial thrust against the nut in the direction opposite to the direction in which the nut bears axially against the bottom of the housing.
The means for fastening the plate on the body perform three functions: preventing the plate from separating from the body; positioning the nut relative to the body; and preventing the plate from turning on the body when the nut is co-operating with the bolt. The plate has a through barrel for passing the screw of the bolt that co-operates with the nut. The barrel is arranged at the bottom of the housing which it extends towards the seat face of the plate. In order to perform all three functions, the fastener means usually include at least a pair of fastener members that are arranged on either side of the barrel. The fastener members make use of said attachment members such as rivets or screw, for example, that engage spaced-apart points both on the plate and on the body. It is also known to make use of cementing means between the plate and the body, in addition to or as a replacement for the attachment members. Merely replacing the attachment members by cementing means performs the function of preventing the plate from separating from the body, but it is difficult to implement so that the cement on its own also performs the other two functions of the fastener means.
For prior art that is close to the present invention, reference may be made to document US 2009/103997 (T. Csik; I. Komsitsky) that describes such a fastener device between a nut and a body and making use of an assembly plate.
By way of indication, reference may also be made to document US 2004/202523 (T. Csik), which discloses a more complex solution for fastening a nut on a body making use of a clip instead of a plate. The clip carries the nut and is fastened to the body by means of two hinged branches forming parts thereof. The branches are fitted with co-operating mutually fitting members for holding the clip in the closed position, bearing respectively against two opposite faces of the body. The fitting members are arranged as a barrel of one of the branches for receiving a hollow cylinder of the other branch. The barrel and/or the cylinder pass through the body via an orifice for passing the screw that co-operates with the nut. The fitting members are used to center the clip on the body, while the hinged zoned between the branches is used to constitute an obstacle to the clip turning by pressing laterally against an edge face of the body. Such a solution that is mentioned by way of example is bulky, expensive, complex to implement, and can only be used near the margin of a plane body.
The use of an assembly plate remains a preferred solution, in particular concerning savings in manufacturing costs and in costs of implementing the fastener device, and also concerning the possibilities of optimizing application of the fastener device. Nevertheless, it is necessary to find a compromise between various constraints.
The costs of manufacturing the plate must be as small as possible, without affecting its reliability and long-lasting to perform all of the functions it is required, in particular concerning the ways in which it is fastened to the body. It is desirable to limit the number and the complexity of manufacturing operations that lead to providing the plate. For example, when fastening is performed by riveting or by screwing the plate to the body, it is necessary to provide at least three orifices formed through the plate, including a middle orifice for passing the screw that co-operates with the nut and two lateral orifices for passing attachment members that prevent the plate from turning on the body. Countersinking needs also to be provided in the plate for receiving the attachment members. Such operations performed on the plate increase manufacturing costs that it is desirable to keep down.
It is also desirable to limit the weight of the fastener device, and in particular of the plate and its means for fastening it to the body. The plate is commonly obtained from a sheet of inexpensive metal material, which is then shaped by cutting and folding and then machined in order to provide the orifices in the plate. A solution that is advantageous in terms of reducing the weight of the plate consists in forming it by molding a plastics material. Nevertheless, it is still necessary for the ways in which the plate is fastened to be of weight and of cost that are limited, and their arrangements need to be as simple as possible in order to enable it to be used easily and at low cost.
The means for fastening the plate on the body give rise to deterioration of the body, which it is desirable to avoid. The various functions that are to be performed by the means for fastening the plate to the body need to be obtained as well as possible, in a manner that is reliable and long-lasting, while not making the structure of the plate more complicated, and while limiting degradation of the body. It is desirable to organize the plate so as to enable it to be fastened to the body while avoiding risks of corrosion as well as possible, which risks may be induced by the plate or by the attachment members, in particular when they are constituted by rivets or analogous metal attachment members.
It is also desirable for the plate to be easily removable from the body on which it is fastened, should that be necessary, e.g. to perform a maintenance operation. The operations of manufacturing the plate and the operations that need to be performed in order to install it on the body, or indeed in order to remove it, if necessary, must be small in number and easy to implement.
The organization of the plate must enable it to be adapted easily to receiving any kind of nut, and in particular regardless of the means with which the nut is intrinsically provided for preventing it from turning inside the housing included in the plate. Such adaptation seeks specifically to simplify the number of different part references for fastener devices that associate a nut in co-operation with a plate, it being desirable for the variety of plates to be as small as possible for some given number of specific nuts. The way the plate is organized should also tend to make it as compact as possible, while nevertheless facilitating the implementation of the operations needed for installing it on the body.